Scanning microscope

Abstract

A scanning microscope includes an objective arranged in an illuminating beam path to focus an illuminating light bundle onto a sample. A scanning unit is arranged upstream of the objective to deflect the illuminating light bundle such that it is focused by the objective executes a scanning movement on the sample. A detection unit is arranged in a detection beam path to receive a detection light bundle not deflected by the scanning unit. For spectral influencing of the detection light bundle, the detection unit contains a spectrally selective component which has an active surface with a spectral edge which varies with the location of incidence of the detection light bundle on the active surface. The active surface is arranged in the detection beam path at the location of an image of an objective pupil, or in a position at which a variation of the spectral edge is compensated for.

The invention claimed is: 
     
       1. A scanning microscope comprising:
 an objective arranged in an illuminating beam path and configured to focus an illuminating light bundle onto a sample; 
 a scanning unit arranged upstream of the objective in the illuminating beam path and configured to deflect the illuminating light bundle in such a way that the illuminating light bundle focused by the objective executes a scanning movement on the sample; and 
 a detection unit arranged in a detection beam path and configured to receive a detection light bundle not deflected by the scanning unit, wherein for spectral influencing of the detection light bundle, the detection unit contains at least one spectrally selective component which has an active surface with a spectral edge which monotonically varies with a variation of a location of incidence of the detection light bundle on the active surface, 
 wherein the active surface of the spectrally selective component is arranged in the detection beam path obliquely to the optical axis of the detection beam path in a position at which a monotonic variation of the spectral edge of the active surface, caused by a variation of an angle of incidence at which the detection light bundle strikes the active surface occurring as a result of the scanning movement of the illuminating light bundle, is opposed to and compensated for, at least in part, by the monotonic variation of the spectral edge of the active surface, which is caused by the variation of the location at which the detection light bundle strikes the active surface. 
 
     
     
       2. The scanning microscope according to  claim 1 , wherein the active surface of the spectrally selective component along the optical axis of the detection beam path has a spacing (Δz) from the location of the image of the objective pupil, which is predetermined depending on the variation of the angle of incidence of the detection light bundle. 
     
     
       3. The scanning microscope according to  claim 2 , wherein the spacing Δz>0 is predetermined in such a way that for all scanning angles ϑ the following condition is fulfilled:
   Δ z≤ 2 ES (ϑ,φ)/ ED  sin(ϑ+φ)/sin(ϑ),  (1)
 
 
       wherein ES(ϑ, φ) designates the variation of the spectral edge of the active surface occurring at the scanning angle ϑ and an angle φ, ED designates the change in the spectral edge per section on the active surface and φ designates the angle, at which the active surface is arranged with respect to the optical axis of the detection beam path. 
     
     
       4. The scanning microscope according to  claim 2 , wherein the spacing is predetermined in such a way that a deviation of the spectral edge from a desired edge position is as small as possible for all the scanning angles. 
     
     
       5. The scanning microscope according to  claim 1 , wherein the active surface of the spectrally selective component is arranged in the detection beam path in such a way that the surface normal of the active surface to the optical axis of the detection beam path is inclined by a predetermined angle. 
     
     
       6. The scanning microscope according to  claim 5 , wherein the predetermined angle is equal to or less than 65°. 
     
     
       7. The scanning microscope according to  claim 1 , wherein the active surface of the spectrally selective component is configured in such a way that the spectral edge varies substantially linearly with the angle of incidence at which the detection light bundle strikes the active surface. 
     
     
       8. The scanning microscope according to  claim 1 , wherein the angle of incidence, which varies according to the scanning movement of the illuminating light bundle and at which the detection light bundle strikes the active surface of the spectrally selective component, is limited to an angle range, in which the location of the incidence of the detection light bundle on the active surface varies approximately linearly with the angle of incidence. 
     
     
       9. The scanning microscope according to  claim 1 , wherein the at least one spectrally selective component comprises at least one beam splitter and/or at least one edge filter. 
     
     
       10. The scanning microscope according to  claim 9 , wherein the at least one edge filter comprises at least one shortpass filter, at least one longpass filter and/or at least one bandpass filter. 
     
     
       11. The scanning microscope according to  claim 10 , wherein the bandpass filter is formed from a shortpass filter and a longpass filter, which are arranged one behind the other along the optical axis of the detection beam path. 
     
     
       12. The scanning microscope according to  claim 1 , wherein the active surface of the spectrally selective component is configured in such a way that the spectral edge along a variation axis varies linearly or non-linearly with the location of the incidence of the detection light bundle. 
     
     
       13. The scanning microscope according to  claim 12 , wherein the spectral edge of the active surface along the variation axis varies linearly with the location of the incidence of the detection light bundle if the active surface is arranged at the location of an image of the objective pupil, and varies non-linearly if the active surface is arranged at the position at which the variation of the spectral edge caused by the variation of the angle of incidence is compensated for. 
     
     
       14. The scanning microscope according to  claim 12 , wherein the detection unit has an optical system arranged upstream of the spectrally selective component in the detection beam path, the optical system having a different optical effect in a direction parallel to the variation axis than in a direction perpendicular to the variation axis. 
     
     
       15. The scanning microscope according to  claim 1 , wherein the detection unit includes at least two detection modules, the at least one spectrally selective component comprising at least one beam splitter, which is configured to feed the detection light bundle, spectrally separated, to the two detection modules. 
     
     
       16. The scanning microscope according to  claim 15 , wherein the at least one beam splitter comprises at least two beam splitters, of which one is arranged in the detection beam path upstream of the image of the objective pupil at a predetermined spacing and another one is arranged downstream of the image of the objective pupil at the same spacing. 
     
     
       17. The scanning microscope according to  claim 16 , wherein the detection unit has a beam splitter cascade, which is formed by the at least one spectrally selective component and comprises at least a first beam splitter and a second beam splitter, and has at least a first detection module, a second detection module and a third detection module, the first beam splitter feeding the detection light bundle, spectrally separated, by transmission to the first detection module and by reflection to the second beam splitter, and the second beam splitter feeding the detection light bundle reflected by the first beam splitter, spectrally separated, by transmission to the second detection module and by reflection, directly or indirectly via a further beam splitter, to the third detection module. 
     
     
       18. The scanning microscope according to  claim 17 , wherein the beam splitters are configured in such a way that the wavelengths of the spectral proportions of the detection light bundle, which the beam splitters feed to the respective associated detection modules in each case by transmission, successively reduce within the beam splitter cascade. 
     
     
       19. The scanning microscope according to  claim 15 , wherein the at least one beam splitter includes at least two beam splitters including at least one first beam splitter, which is arranged in the detection beam path upstream of the image of the objective pupil, and at least one second beam splitter, which is arranged in the detection beam path downstream of the image of the objective pupil. 
     
     
       20. The scanning microscope according to  claim 19 , wherein the first and the second beam splitter have the same dispersion and are arranged at the same spacing from the image of the object pupil, the dispersion corresponding to a change of the spectral edge per section on the active surface. 
     
     
       21. The scanning microscope according to  claim 19 , wherein the at least one first beam splitter comprises at least two beam splitters which are arranged upstream of the image of the objective pupil at various spacings and have a different dispersion, and/or wherein the at least one second beam splitter comprises at least two beam splitters which are arranged downstream of the image of the objective pupil at different spacings and have a different dispersion. 
     
     
       22. The scanning microscope according to  claim 16 , wherein the at least one spectrally selective component comprises at least one edge filter which, in at least one of the detection modules which has a detector without a further imaging optical system, adjoins the beam splitter, the at least one edge filter being arranged upstream of the detector and the active surface being arranged substantially at the location of the image of the objective pupil. 
     
     
       23. The scanning microscope according to  claim 1 , wherein the detection unit contains at least one aspherical lens. 
     
     
       24. The scanning microscope according to  claim 1 , wherein the active surface of the spectrally selective component is polarization-sensitive. 
     
     
       25. The scanning microscope according to  claim 1 , wherein the spectrally selective component is adjustable to change the location of the incidence of the detection light bundle on the active surface. 
     
     
       26. The scanning microscope according to  claim 1 , wherein the objective is configured both to focus the illuminating light bundle onto the sample and to receive the detection light bundle. 
     
     
       27. The scanning microscope according to  claim 1 , wherein the objective is only configured to focus the illuminating light bundle onto the sample, and wherein an optical system is arranged in the detection beam path so as to receive the detection light bundle. 
     
     
       28. A scanning microscope comprising:
 an objective arranged in an illuminating beam path and configured to focus an illuminating light bundle onto a sample; 
 a scanning unit arranged upstream of the objective in the illuminating beam path and configured to deflect the illuminating light bundle in such a way that the illuminating light bundle focused by the objective executes a scanning movement on the sample; and 
 a detection unit arranged in a detection beam path and configured to receive a detection light bundle not deflected by the scanning unit, wherein for spectral influencing of the detection light bundle, the detection unit contains at least one spectrally selective component which has an active surface with a spectral edge which varies with a variation of a location of incidence of the detection light bundle on the active surface, 
 wherein the active surface of the spectrally selective component is arranged in the detection beam path in a position at which a variation of the spectral edge of the active surface, caused by a variation of an angle of incidence at which the detection light bundle strikes the active surface occurring as a result of the scanning movement of the illuminating light bundle, is opposed to and compensated for, at least in part, by the variation of the spectral edge of the active surface, which is caused by the variation of the location at which the detection light bundle strikes the active surface, 
 wherein the active surface of the spectrally selective component along the optical axis of the detection beam path has a spacing (Δz) from the location of the image of the objective pupil, which is predetermined depending on the variation of the angle of incidence of the detection light bundle, and 
 wherein the spacing Δz>0 is predetermined in such a way that for all scanning angles ϑ the following condition is fulfilled: 
 
       
         
           
             
               
                 
                   
                     
                       
                         Δ 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         z 
                       
                       ≤ 
                       
                         2 
                         ⁢ 
                         
                           
                             ES 
                             ⁡ 
                             
                               ( 
                               
                                 ϑ 
                                 , 
                                 φ 
                               
                               ) 
                             
                           
                           ED 
                         
                         ⁢ 
                         
                           
                             sin 
                             ⁡ 
                             
                               ( 
                               
                                 ϑ 
                                 + 
                                 φ 
                               
                               ) 
                             
                           
                           
                             sin 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               ϑ 
                               ) 
                             
                           
                         
                       
                     
                     , 
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
       wherein ES(ϑ, φ) designates the variation of the spectral edge of the active surface occurring at the scanning angle ϑ and an angle φ, ED designates the change in the spectral edge per section on the active surface and φ designates the angle, at which the active surface is arranged with respect to the optical axis of the detection beam path.